Process for the stable dispersion of silicon dioxide in solutions of cellulose ethers



United States Patent PROCESS FOR THE STABLE DISPERSION OF SILI- CON DIOXIDE IN SOLUTIONS OF CELLULOSE ET HERS Ernest Ferdinand Zaalberg van Zelst, Nimeguen, Netherlands, assignor to Kunstzijdespinnerij Nyma N. V., Nimeguen, Netherlands, a limited liability company of the Netherlands No Drawing. Application December 1, 1953, Serial No. 395,624

Claims priority, application Netherlands December 9, 1952 13 Claims. (Cl. 106-193) The invention provides a process to obtain a mixture of a cellulose ether, e. g. sodium carboxy methyl cellulose and SiO2, and more particularly to a process of preparing a stable SiOz dispersion in aqueous cellulose ether solutions. If commercial colloidal SiOz solutions are added to sodium carboxy methyl cellulose, the colloidal SiOa particles easily coagulate and settle down. Moreover the use of these special SiOz solutions is expensive due to the rather complicated manner in which these are to be prepared. In the process according to toe invention the separate preparation of colloidal SiOz solutions is entirely avoided, while the SiOz dispersion obtained is completely stable.

The invention furthermore comprises a process for sizing yarns, consisting herein that the sizing is carried out with the above mentioned stable dispersion of SiO2 in a solution of a cellulose ether.

In accordance with the invention, the cellulose ether, i. e. sodium carboxy methyl cellulose is prepared in conventional manner and during one of the stages of preparation of the sodium carboxy methyl cellulose an alkaline solution of a silicate is added to the reaction mixture and thereupon neutralization with acid, preferably a non-oxidizing acid having a hydrogen ion concentration of not less than 1.753 takes place.

The alkaline silicate solution may be added and thereupon the alkali of the reaction mixture as well as that of the silicate solution may be neutralized simultaneously. If desired the alkaline silicate solution may also be added to the already neutralized reaction mixture.

If one wants to liberate the neutralized SiOz containing reaction mixture from the admixed salts, the mixture may be purified in the usual manner by extraction with alcohol. It is also possible to obtain more immediately a purified product by extracting the reaction mixture with acidified alcohol before the neutralization.

The invention is not restricted to obtaining stable SiOz dispersions in a sodium carboxy methyl cellulose solution, but provides for all cases in which one wants to disperse SiOz in a stable manner in solutions of cellulose ethers, such as carboxyalkyl-, hydroxyalkyland alkylcelluloses. The invention is further elucidated by the following examples:

Example I To 644 g. of soda cellulose in crumbled form, containing approximately 30% of cellulose and approximately of NaOH, 166 g. of CHzClCOONa were added. The mixture obtained in this manner was ground during 6 hours in a laboratory mill of the Werner-Pfleiderer type. Thereupon 272 g. of waterglass containing 35% of SiOz and 17% of NazO were added. The mass was neutralized with acetic acid and dried.

The mixture obtained contained 13% of SiOa and 31% 1% solution of a mixture of 100 parts of ice Point of time at which the settling of SiO; particles can be clearly observed 7 days after the preparation of 1% solution of a mixture of 100 parts of OM the solution.

0 and 15 parts of S10: according to the invention.

2 hours after the preparation of CMC and 15 parts of S102, added in the solution. the form 01 a colloidal SiO; solution from the market.

The favorable behavior of the solution of the SiO2- CMC mixture according to the invention was found also when the settling test was carried out at C.

Example 11 In the same manner as indicated in Example I a dried SiOz containing CMC was prepared and thereupon extracted with 60% aqueous ethanol and thereupon dried again. From the dried and purified product thus obtained a 1% dispersion was made and compared in the same manner as indicated in Example I in respect of the stability with a 1% solution of CMC prepared and purified in the same mannerbut without the addition of waterglass to which a colloidal dispersion containing only SiO2 and water was added in such a quantity that 15 parts of S102 were present to 31 parts of pure CMC. The clear settling down of the SiOz could be observed in the former dispersion after 7 days, in the latter dispersion after 4 hours.

Example III In the same manner as indicated in Example I CMC was prepared followed by the addition of waterglass. The mixture thus obtained was suspended in 60% aqueous ethanol containing moreover a measured quantity of strong HCl, necessary to neutralize the NaOH of the soda cellulose and of the waterglass. After centrifugation and drying a purified SiOz-containing CMC was obtained which was tested in the same manner as indicated in Example H. In this test of the stability of the dispersion the same results as indicated inExample II were found.

Example IV Woolen yarn No. 20 (metric number) was sized with a SiOz dispersion in a solution of sodium carboxy methyl cellulose prepared according to Example I (5% solution of the technical CMC-SiOz mixture). The sized yarn had a tensile strength of 285 g. while the strength of the nonsized yarn was 221 g. The elongation of the sized yarn was 17.9%, of the non-sized yarn 10.5%. The weavability of the yarn was excellent. Not only the number of warp breakage was considerably reduced but also slipping of knots was eliminated.

What is claimed is:

1. A process for preparing a mixture of a cellulose ether selected from the group consisting of lower carboxyalkyl, lower hydroxyalkyl and lower alkyl cellulose, and particulate SiO2, comprising the steps of adding a waterglass solution to the cellulose ether and neutralizing the mixture with a non-oxidizing acid having a hydrogen ion concentration of not less than 1.753 10- 2. A process of preparing a mixture of sodium carboxy methyl cellulose and particulate SiO2, comprising the steps methyl cellulose and neutralizing the mixture with a-non- 1 oxidizing acid having a hydrogen ion concentration of not less than 1.753Xlv 3. A process for preparing a-mixture of "a cell-ulose ether selected from the group consisting of lower car'- boxyalkyl, lower hydroxyalkyl 1 and lower alkyl cellulose, and particulate SiOz, comprising the steps of reacting alkali cellulose with CHzClCOONa, addingwaterglass to the reaction product, and further adding a non-oxidizing acid having a hydrogen ion concentration of not less than l.753 to neutralize the reaction mixture.

4. A process for preparing a mixture of a cellulose ether selected from the group consisting of lower carboxyalkyl, lower hydroxyalkyl and lower alkyl cellulose, and particulate SiOz, comprising the steps of reacting alkali cellulose with CHzClCOONa, adding waterglass to the reaction product, and further adding an aqueous acidified alcohol having a hydrogen ion concentration of not less than l.753 10- to the mixture to neutralize 'the same and extract admixed salts therefrom.

5. A process for preparing a mixture of a cellulose ether selected from the group consisting of lower carboxyalkyl, lower hydroxyalkyl and lower alkyl cellulose, and particulate SiOz, comprising the steps of reacting alkali cellulose with CHzClCOONa, adding waterglass to the reaction product, further adding a non-oxidizing acid having a hydrogen ion concentration of not less than 1.753 x 10- to neutralize the reaction mixture, and treating the neutralized mixture with aqueous alcohol to extract admixed salts therefrom.

6. A process for preparing a stable dispersion of particulate SiOz in a solution containing a cellulose ether selected from the group consisting of lower carboxyalkyl, lower hydroxyalkyl and lower alkyl cellulose, comprising the steps of admixing alkali cellulose, an etherifying agent and a waterglass solution, the alkali cellulose and the etherifying agent reacting to form the cellulose ether, neutralizing the mixture with a non-oxidizing acid having a hydrogen ion concentration of not less than 1.753 10 drying the neutralized mixture, and dissolving the dried mixture in water.

7. A process for preparing a stable dispersion of particulate SiOz ina solution containing sodium carboxy methyl cellulose, comprising the steps of admixing alkali cellulose, an etherifying agent and a waterglass solution,

8. A process forpreparing a stable dispersion of ,par-

ticulate SiOz in a solution containing a cellulose ether selected from the group consisting of lower carboxyalkyl,

lower hydroxyalkyl and lower alkyl cellulose, comprising the steps of admixing alkali cellulose, an etherifying agent and a waterglass solution, the alkali cellulose and the etherifying agent reacting to form the cellulose ether, neutralizing and extracting admixed salts from the mixture with an aqueous acidified alcohol having a hydrogen ion concentration of not less than 1.753 l0 drying the neutralized mixture, and dissolving the dried mixture in water.

9. A process for preparing a stable dispersion of particulate SiOz in a solution containing a cellulose ether selected from the group consisting of lower carboxyalkyl, lower hydroxyalkyl and lower alkyl cellulose, comprising the steps of admixing alkali cellulose, an etherifying agent and a waterglass solution, the alkali cellulose and the etherifying agent reacting to form the cellulose ether, neutralizing the mixture with a non-oxidizing acid having a hydrogen ion concentration of not less than 1.753 l0 extracting admixed salts from the neutralized mixture with an aqueous alcohol, drying the mixture, and dissolving the dried mixture in Water.

10. A stable dispersion of particulate SiOz in a cellulose ether selected from the group consisting of lower carboxyalkyl, lower hydroxyalkyl and lower alkyl cellulose, comprising an aqueous solution of a neutralized reaction product of the cellulose ether with water-glass and a nonoxidizing acid having a hydrogen ion concentration of not less than 1.753 10- 11. A stable dispersion of particulate SiOz in sodium carboxy methyl cellulose, which contains about 13% of SiOz and 31% of the carboxy methyl cellulose, comprising an aqueous solution of a neutralized reaction product of the carboxy methyl cellulose with waterglass and a nonoxidizing acid having a hydrogen ion concentration of not less than 1.753 10- 12. A stable dispersion of particulate SiOz in a cellulose ether selected from the group consisting of lower carboxyalkyl, lower hydroxyalkyl and lower alkyl cellulose, comprising essentially 99 parts of water and 1 part of a neutralized reaction product of the cellulose ether with waterglass and a non-oxidizing acid having a hydrogen ion concentration of not less than 1.753 10* 13. A textile yarn of improved tensile strength sized with a stable dispersion as defined in claim 10.

References Citedin the file of this patent UNITED STATES PATENTS 2,086,729 Moss July 13, 1937 2,433,833 Auer Jan. 6, 1948 2,649,388 Wills Aug. 18, 1953 

1. A PROCESS FOR PREPARING A MIXTURE OF A CELLULOSE ETHER SELECTED FROM THE GROUP CONSISTING OF LOWER CARBOXYALKYL, LOWER HYDROXYALKYL AND LOWER ALKYL CELLULOSE, AND PARTICULATE SIO2, COMPRISING THE STEPS OF ADDING A WATERGLASS SOLUTION TO THE CELLULOSE ETHER AND NEUTRALIZING THE MIXTURE WITH A NON-OXIDIZING ACID HAVING A HYDROGEN ION CONCENTRATION OF NOT LESS THAN 1.753X10-5. 